Another park is the Gunung Mulu National Park, located on the border with Brunei.
It is a world heritage site that includes numerous caves and karst formations located in a mountainous rainforest setting.

Within the park is the largest natural enclosed space in the world-a place called the Sarawak Chamber. It is large enough to fit several jumbo jets inside.

Many visitors go to to explore numerous other caves, some exposing parts of a long underground river.